Rotating lock for automatic firearm



Feb. 25, 1969 R. c. sEccoMBE 3,429,223

ROTATING LOCK FOR AUTOMAT-IC FIREARM Sheet Filed Feb. 28, 1968 Feb' 25 1969 R. c. sEccoMaE ROTATING LOCK FOR AUTOMATIC FIREARM Sheet of' 2 Filed Feb. 28, 1968 n. Mm?. if fw V1.0 @L w, y. i@

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QQ wm, www @Nv United States Patent O F'ce 3,429,223 ROTATING LOCK FOR AUTOMATIC FIREARM Robert Charles Seccombe, 946 Glencoe Road,

. Glencoe, Ill. 60022 'Continuation-impart of application Ser. No. 576,349, Aug. 31, 1967. This application Feb. 28, 1968, Ser. No. 708,939 U.S. Cl. 89-172 7 Claims Int. Cl. F41d 5/12 ABSTRACT OF THE DISCLOSURE A rotating lock for a recoil operated firearm including an ejector stud affixed to the receiver of the firearm and engaging a substantially axial cam track formed in the surface of the firearm bolt. The cam track is an open ended cam track being open at the front end of the bolt and terminating at a point adjacent the rear end of the bolt, and has its rear portion radially offset from the front portion and connected thereto by a laterally curved segment. The opposed surfaces of the laterally curved segment are formed at different angles to the axis of the bolt, the recoil angle being shallower than the counter recoil angle to facilitate rapid unlocking and recoil of the bolt and to allow counter recoil and locking of the bolt withthe barrel and chambering of the cartridge without deformation or violence. The ejector stud is positioned to engage the base of a spent cartridge to eject it from the firearm.

This application is a continuation-in-part of my application Ser. No. 576,349, yfiled Aug. 3l, 1967, now abandoned.

Background of the invention This invention relates to a rotating lock for a recoil operated firearm and is particularly concerned with simple, efiicient means for interlocking the bolt and barrel for battery and for disengaging the bolt from the barrel after firing, to permit ejection of the used cartridge case and insertion of a new cartridge.

The idea of rotating the bolt of a firearm relative to the barrel for interlocking and disengaging the bolt and barrel is well known, but the mechanisms for accomplishing the desired result automatically are complicated and relatively expensive. The number of parts required makes the tooling and assembly expensive and also increases the frequency of repairs.

It is desirable to provide a rotating lock, particularly for small automatic firearms such as rifles, and pistols which is simple, which has few parts and which operates reliably and efficiently. Such a rotating lock should not upset the balance of such weapons, should not add rnaterially to their cost and should be readily adaptable for use in such weapons without requiring substantial alteration in their design.

Summary of the invention In accordance with the present invention, there is provided such a simplified, reliable rotating lock mechanism which is adaptable for use with automatic firearms, particularly smaller weapons. The lock mechanism incorporates few parts, is unlikely to need repair or adjustment, but which allows such repairs to be accomplished rapidly and with little expense when required.

Rotation of the bolt is effected by an ejector stud affixed to the receiver and extending therethrough into a generally axially cam track formed in the surface of the bolt. The cam track is an open ended track extending from the front of the bolt and terminating adjacent the rear end of the bolt. The rear portion of the cam track 3,429,223 Patented Feb. 25, 1969 is radially offset from the front portion and connected thereto by a laterally curved segment having opposed surfaces formed at different angles to the axis of the bolt. The recoil cam surface of the laterally curved segment is formed at a shallower angle than the counter recoil surface of the segment which is formed generally at an angle of about 30-33 degrees.

The shallow recoil angle allows the bolt to disengage from the barrel after a short dwell time which allows the chamber pressure to reach a safe level and allows the bolt to rotate and disengage from the barrel rapidly and smoothly to utilize the remaining pressure for completing the recoil of the bolt. During counter recoil, the bolt moves forward towards the barrel until the stud engages the counter recoil surface of the lateral portion, at which point the axial movement of the bolt is slowed down due to the steeper angle of this surface. The bolt rotates and locks within the barrel extension, and a new cartridge is chambered without deformation due to the reduced speed of the now locked together bolt and barrel, also reducing the possibility of the locked together bolt and barrel bouncing out of battery as counter recoil movement terminates.

The ejector stud, which can be located at a suitable angle relative to the horizontal, is so positioned that the forward edge thereof extends beyond the front end of the bolt during the last stages of recoil. As the front edge of the bolt recoils past the ejector stud, the stud engages the base of the empty cartridge causing it to eject through appropriate apertures in the receiver.

Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention, from one embodiment thereof, from the claims and from the accompanying drawings, in which each and every detail shown is fully and completely disclosed as part of the specification, in which like reference numerals refer to like parts, and in which:

FIGURE 1 is a fragmentary side view, partially in section showing a firearm embodying the present invention, with conventional components omitted for clarity, showing the bolt and barrel locked together;

FIGURE 2 is a top view of the firearm shown in FIG- URE 1;

FIGURE 3 is a side view similar to FIGURE l showing the bolt unlocked from the barrel and in its rearmost position;

FIGURE 4 is a side view similar to FIGURE 3 from the opposite side; and

FIGURE 5 is a sectional view taken along lines 5-15 of FIGURE 4.

Detailed description Referring now to the drawings, there is shown a portion of a firearm embodying the present invention including a receiver 10 in which is disposed for axial reciprocable movement a barrel 12 and a bolt 14. The rear end of the barrel 12 is secured to a barrel extension 16 in any suitable manner. The barrel extension 16 and barrel 12 may be integral with each other if desired, but in the illustrated embodiment are shown as being screwed into place. The barrel extension 16 is a tubular sleeve-like member having the forward portion 18 of its inner surface threaded to engage threads 20 on the outer surface of the rear end of the barrel 12.

The rear end of the barrel extension 16 is provided with an inwardly extending annular flange 22 that is interrupted by at least one axial extending slot 24. When the barrel extension 16 is secured to the barrel 12, the inner surface of the annular flange 22 is spaced rearwardly a short distance from the rear end of the barrel 12 to define a locking space 26. In firing the firearm, the bolt 14 and barrel 12 are locked together when in battery and are separated from each other after firing to permit ejection of a spent cartridge case 28 and insertion of a new cartridge before the bolt 14 and barrel 12 are returned to battery and locked together. The present invention is not concerned with insertion of a new cartridge or with the firing mechanism, and, therefore, these features have been omitted for clarity.

Locking of the barrel 12 and bolt 14 together is effected by a pair of diametrically opposed lugs 30 extending radially outwardly from the forward edge 32 of the bolt 14. The lugs 30 are slightly narrower than the axial slot 24 formed in the annular flange 22 of the barrel extension 16 and are slightly thinner than the depth of the locking space 26 between the annular flange 16 and the rear end of the barrel 12, thereby permitting rotation of the bolt 14 relative to the barrel 12 when the bolt lugs 30 are disposed in the locking space 26.

As can be readily appreciated, the barrel 12 and bolt 14 may be locked together by aligning the lugs 30 with the axial slot 24 and passing the front end 32 of the bolt 14, including the lugs 30, past the annular flange 22 until the lugs 30 are disposed in the locking space 26. Rotation of the bolt 14 relative to the barrel 12 will lock the two together since the lugs 30 will then be disposed between the rear of the barrel 12 and annular fiange 22 on the barrel extension 1'6. Unlocking of the bolt 14 from the barrel 12 is effected by rotation of the bolt 14 until the bolt lugs 30 are aligned with the axial slot 24 to allow removal of the bolt 14 from the barrel 12.

Rotation of the bolt 14 relative to the barrel 12 is effected by an ejector stud 34 which is suitably affixed to the receiver acting in conjunction with a generally axial open ended cam track 36 formed in the surface of the bolt 14. The cam track 36 includes a general axial rearward portion extending from a point adjacent the rear end of the bolt 14 and radially offset from a forward portion 40 which exits at the front face 10 of the bolt 14.

The rearward portion 38 of the cam track 36 is connected to the forward portion 40 by a short lateral segment 42. The opposed surfaces 44, 46 of the lateral segment 42 are formed at different angles to the axis of the bolt 14, the recoil unlocking surface 44 being formed at a shallower angle to the axis than the counter-recoil locking surface 46 which is typically formed at an angle of 30-35 degrees to the axis of the bolt 14.

The relative radial position of the axial slot 24, the locking lugs 30, the cam track 36 and the ejector stud 34 are selected so that the ejector stud can eject a spent cartridge case upon recoil of the bolt 14 as explained hereinbelow. Typically, if the spent cartridge case is to be ejected out the side of the firearm, the stud will be positioned at an angle of about 69 from the top of the firearm, although the ejector stud could be located between about 42 to 72 degrees, the selection of the angle being dependent on other design features of the bolt 14.

The rotating lock may be more clearly understood in conjunction with a description of the firing cycle of a firearm commencing with the firearm in battery. At this point the bolt 14 and barrel 12 are locked together and the ejector stud 34 is disposed at the rear of the cam track 36, as most clearly seen in FIGURE 1 of the drawing. Upon firing, the bolt 14 and barrel 12 recoil in unison moving rearwardly as a unit for a time coresponding to the length of the rearward portion 38 of the cam track 36. This distance, the dwell period, is to allow for the pressure in the chamber to reach a safe level before for unlocking the bolt 14, to prevent damaging the mechansms in the firearm.

At a point where the chamber pressure is at a desirable operating level, the bolt 14 is unlocked from the barrel 12 to continue its recoil free of the barrel 12 as rapidly as possible. Unlocking is effected by the ejector stud 34 coming into contact with the recoil-unlocking surface 44 of the cam track lateral segment 42, the gradual angle of surface 44 permits rotation of the bolt relative to the barrel during recoil without jamming. The bolt 14 completes its rotation, i.e., the lateral segment 42 passes by the ejector stud 34, at a point where recoil of the barrel 12 is terminated by any suitable means known in the art. Since the rotation of the bolt has aligned the bolt lugs with the axial slot in the barrel extension, the bolt is free to continue its recoil smoothly and without binding.

Referring now to FIGURES 3 and 4 where the rearm is shown with the bolt 14 in the full recoil position, it should be noted that in this position the most forward portion of the ejector stud 34 extends past the forward edge 32 of the bolt 14. As a result, when the bolt 14 reaches the end of its recoil movement, the ejector stud 34 hits the base of the spent cartridge case 28 being extracted by the recoiling bolt 14 to expell it away from the bolt face 32 and out of the firearm.

With a new cartridge in place, counter-recoil of the bolt 14 commences under any suitable force, known in the art, such as a spring (not shown). The bolt 14 moves forward until the locking lugs 30 pass through the axial slot 24 into the locking space 26. At this point the ejector stud 34 engages the counter-recoil locking surface 46 of the lateral segment 42, which as explained above is formed at a greater angle to the bolt axis than the unlocking recoil surface 42.

The sharper angle of the counter-recoil locking surface 46 slows down the forward movement of the bolt 14 while simultaneously rotating the bolt to lock the bolt 14 and barrel 12 together. The slowing down of the forward -movement of the bolt 14 as it engages the rear end of the barrel 12 reduces the likelihood of the bolt and barrel being bounced out of battery and also allows chambering of the new cartridge without deformation or other distortion.

Thus, there has been described a rotating lock for automatic firearm which simply and effectively unlocks and locks a bolt and barrel during recoil and counter recoil while at the same time controlling the speed of recoil and allowing for locking of the bolt and barrel together without damaging parts of the firearm or the cartridge being chambered. In addition, the simple structure for effecting relative rotation of the bolt to the barrel is also used to eject a spent cartridge from the firearm.

I claim:

1. In an automatic firearm including a receiver, a barrel, a bolt axially movable within said receiver, a rotating lock comprising means on the forward end of said bolt engageable with said barrel for locking the bolt and barrel together upon rotation of the bolt relative to said barrel and for unlocking the bolt and barrel upon counterrotation of the bolt relative to the barrel, a generally axial cam track formed in the surface of said bolt, said cam track having a forward generally axial portion and a rearward generally axial portion radially offset from said forward portion and connected thereto by a lateral portion, the opposed surfaces of said lateral portion being formed at different angles to the axis of the bolt, and an ejector-stud affixed to said receiver in engaging relation with said cam track, and cooperating therewith for effecting said unlocking rotation of said bolt a't a first rate during recoil, and for effecting said locking counter-rotation of said bolt at a rate different lfrom said first rate during counter-recoil to lock said bolt and barrel together.

2. The rotating lock of claim 1 in which the unlocking surface of said cam track lateral portion engaging said ejector-stud during recoil is formed at a lesser angle than the locking surface of said lateral portion engaging said ejector-stud during counter-recoil.

3. The rotating lock 0f claim 2 in which the locking surface of said cam track lateral portion is formed at an angle of about 30*35 to the bolt axis.

4. The rotating lock of claim 1 in which the ejector-s'tud is disposed at an angle of about 42-72 from the -top of the firearm.

5. The rotating lock of claim 4 in which the ejectorstud is disposed at an angle of about 69 from the top of the firearm.

6. The rotating lock of claim 1 in which said cam track is open at the forward face of said bolt and in which the forward portion of said ejector-stud extends past the front face of said bolt at the end of recoil to engage the base of a spent cartridge case to eject said case from the firearm.

7. An automatic recoil operated firearm comprising in combination a receiver, a barrel, a bolt axially movable within said receiver, means on the forward end of said bolt engageable with said barrel for locking the bolt and barrel together upon rotation of the bolt relative to said Ibarrel and for unlocking the bolt and barrel upon counterrotation of the bolt relative to the barrel, and ejector-stud aixed to said receiver and disposed at an angle of about 69 from the top of the firearm, a generally axial cam track in said bolt engaged by the end of said ejector-stud, said cam track having a forward portion, a rearward portion offset radially from said forward portion and a la'teral portion interconnecting said forward and rearward CII portions, the opposed surfaces of said lateral portion being formed at different angles to the bolt axis, the surface of said lateral portion engaged by said ejector-stud during recoil for causing said unlocking rotation of said bolt being shallower than the other surface of said lateral portion engaged by said ejector-stud during counter-recoil for causing said locking counter-rotation, said other surface being formed at an angle of about 30-33 to the bolt axis, said cam track being open at its forward end whereby the forward portion of said ejector-stud overlaps the front face of said bolt at the end of the bolt recoil to engage the base of a spent cartridge case to eject the case from said lirearm.

BENJAMIN A. BORCHELT, Primary Examiner.

STEPHEN C. BENTLEY, Assistant Examiner.

IUS. Cl. X.R. 42-25 

